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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 18 Abstracts search results
Document:
SP143-05
Date:
May 1, 1994
Author(s):
R. A. Cook and F. E. Fagundo
Publication:
Symposium Papers
Volume:
143
Abstract:
A new type of short-span bridge system has been developed and implemented over the Albermarle Sound south of Edenton, North Carolina. The new system incorporates precast flat-slab sections that are post-tensioned for continuity. The new system has the potential to replace traditional trestle-type bridges constructed using simple-span prestressed beams with a cast-in-place deck. A continuous two-span, half-scale model of the bridge system was built and tested under various load conditions. The bridge was evaluated analytically and experimentally for the transfer load case (dead load plus prestress), the maximum negative moment service load case, cracking load, and ultimate load. The model bridge performed as expected for all cases. Comparisons between analytical and physical models showed good correlation for all types of tests. At service load levels, the bridge exhibited a linear elastic response with no evidence of cracking. The ultimate load and deflections of the new bridge system were readily predicted by standard behavioral models for prestressed concrete.
DOI:
10.14359/4600
SP143-08
S. M. Kulkarni and S. P. Shah
Discusses important issues relevant to high-rate closed-loop testing of reinforced concrete beams. To obtain a high rate of loading from a closed-loop machine, special considerations are required in the design as well as operation of the machine. These issues are discussed briefly. Useful insight into behavior of a specimen in a high-rate closed-loop test is provided by some analytical expressions supplied here for single-degree-of-freedom (SDOF) and multiple-degree-of-freedom (MDOF) specimen systems. Advantages of displacement control over load control are apparent from the expressions obtained. Preliminary results of displacement-controlled tests conducted on reinforced concrete beams at low and high rates are reported. The specimen deformation-versus-time curve in these tests indicates that, for this setup, the test machine used in this project can apply an essentially constant velocity. Crack pattern obtained for the beams as well as inspection of load and specimen deformation signals indicate that the manner of loading was quasi-static (that is, free of inertial effects) even for the high-rate case. The load-deflection curve for the high-rate case exhibits a down-sloping portion after a small plateau.
10.14359/4601
SP143-04
B. Massicotte and A. Picard
Describes details of an extensive monitoring program carried out during the strengthening of the Grand Mere Bridge, a cast-in-place post-tensioned segmental box girder structure built in 1977. The testing program comprised various measurements taken before, during, and after the prestressing application. Electrical strain gages, mechanical strain gages, vibrating wire gages, and thermocouples were among the measuring instruments used. A bridge testing data acquisition system in a vehicle and an autonomous data acquisition system were used, together with manual reading devices. The field measurement program was carried out during strengthening. Some instruments used allow the monitoring of the bridge over a long-term period.
10.14359/4608
SP143-09
R. Y. Miao and W. H. Yang
The interface confining stress between steel tube and core concrete is an important problem in the analysis of the behavior of concrete-filled steel tubes. However, no satisfactory experimental method to measure the interface stress directly has been developed because of the peculiar geometry of concrete-filled steel tubes. In this study, the significance of measuring interface stress is discussed, and the use of hydraulic analogy, or analogous hydraulically loaded control specimens, is introduced. In this paper, the fundamental mechanism, instrumentation, and procedure of hydraulic analogy will be described in detail together with examples.
10.14359/4583
SP143-10
M. Wecharatana and A. P. Ranasinghe
The break-off test is a recently developed nondestructive test for concrete. Although many experimental investigations have been carried out on this test, no in-depth theoretical evaluation has been done. In this study, the behavior of the break-off test specimen is investigated, and the theoretical basis of the test is explored. Based on linear elastic fracture mechanics, a model to predict the strength-manometer reading relationship of the test is proposed and compared with experimental results with good correlation. It was found that the ACI recommendation on the modulus of rupture (MOR) may be very conservative for certain members. The MOR of a rectangular beam is different from that observed from a circular cross section, such as the break-off test specimen. New MOR values are suggested for small rectangular beams and members with circular cross sections.
10.14359/4584
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